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1、BRITISH STANDARD BS ISO 11357-4:2005 Plastics Differential scanning calorimetry (DSC) Part 4: Determination of specific heat capacity ICS 83.080.01 ? Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:16:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS ISO 11357-4:2005 This British Standard w
2、as published under the authority of the Standards Policy and Strategy Committee on 11 January 2006 BSI 11 January 2006 ISBN 0 580 47107 1 National foreword This British Standard reproduces verbatim ISO 11357-4:2005 and implements it as the UK national standard. The UK participation in its preparatio
3、n was entrusted to Technical Committee PRI/21, Testing of plastics, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international publications referred to in thi
4、s document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a con
5、tract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals
6、for change, and keep UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the ISO title page, pages ii to iv, pages 1 to 10, an inside back cover and a back cover.
7、The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. DateComments Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:16:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Reference number ISO 11357-4:2005(E) I
8、NTERNATIONAL STANDARD ISO 11357-4 First edition 2005-09-15 Plastics Differential scanning calorimetry (DSC) Part 4: Determination of specific heat capacity Plastiques Analyse calorimtrique diffrentielle (DSC) Partie 4: Dtermination de la capacit thermique massique BS ISO 11357-4:2005 Licensed Copy:
9、sheffieldun sheffieldun, na, Mon Nov 27 08:16:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:16:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iii Contents Page Foreword iv 1 Scope . 1 2 Normative references. 1 3 Terms and definitions. 1 4 P
10、rinciple. 2 5 Apparatus 3 6 Test specimen. 4 7 Test conditions and specimen conditioning . 4 8 Procedure 4 9 Determination of specific heat capacities 7 10 Precision and bias 7 11 Test report . 7 Annex A (informative) An approximate expression of the specific heat capacity of pure -alumina. 8 Biblio
11、graphy. 10 BS ISO 11357-4:2005 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:16:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iv Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of prepa
12、ring International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in l
13、iaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task o
14、f technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention i
15、s drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 11357-4 was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 5, Physical-chemical proper
16、ties. ISO 11357 consists of the following parts, under the general title Plastics Differential scanning calorimetry (DSC): Part 1: General principles Part 2: Determination of glass transition temperature Part 3: Determination of temperature and enthalpy of melting and crystallization Part 4: Determi
17、nation of specific heat capacity Part 5: Determination of characteristic reaction-curve temperatures and times, enthalpy of reaction and degree of conversion Part 6: Determination of oxidation induction time Part 7: Determination of crystallization kinetics BS ISO 11357-4:2005 Licensed Copy: sheffie
18、ldun sheffieldun, na, Mon Nov 27 08:16:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 1 Plastics Differential scanning calorimetry (DSC) Part 4: Determination of specific heat capacity 1 Scope This part of ISO 11357 specifies methods for determining the specific heat capacity of plastics by different
19、ial scanning calorimetry. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
20、ISO 472, Plastics Vocabulary ISO 11357-1:1997, Plastics Differential scanning calorimetry (DSC) Part 1: General principles ISO 31-0:1992, Quantities and units Part 0: General principles 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 472 and ISO 1135
21、7-1 and the following apply. 3.1 calibration material material of known specific heat capacity NOTE Usually, -alumina (such as synthetic sapphire) of 99,9 % or higher purity is used as the calibration material. 3.2 specific heat capacity (at constant pressure) cp quantity of heat necessary to raise
22、the temperature of unit mass of material by 1 K at constant pressure NOTE 1 It is given by the following equation: cp = m1Cp = m1(dQ/dT)p (1) where m is the mass of material; Cp is the heat capacity; dQ is the quantity of heat necessary to raise the temperature of the material by dT; BS ISO 11357-4:
23、2005 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:16:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 2 subscript p indicates an isobaric process; cp is expressed in kilojoules per kilogram per K (kJkg1K1) or in joules per gram per K (Jg1K1). This equation is valid in a temperature range w
24、here a material shows no first-order phase transition. (dQ/dT) = (dt/dT) (dQ/dt) = (heating rate)1 (heat flow rate) (2) NOTE 2 At phase transitions, there is a discontinuity in the heat capacity. Part of the heat is consumed to produce a material state of higher energy and it is not all used in rais
25、ing the temperature. For this reason, the specific heat can only be determined properly outside regions of phase transitions. 4 Principle 4.1 General Each measurement consists of three runs at the same scanning rate (see Figure 1): 1) a blank run (empty pans in sample and reference holders); 2) a ca
26、libration run (calibration material in sample holder pan and empty pan in reference holder); 3) a specimen run (specimen in sample holder pan and empty pan in reference holder). Key X temperature T or time t 1 blank run 2 calibration run 3 specimen run I isothermal baseline at start temperature Ts I
27、I isothermal baseline at end temperature Tf Figure 1 Schematic drawing of typical DSC curves for specific heat capacity measurement (blank, calibration and specimen runs) after baseline adjustment BS ISO 11357-4:2005 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:16:29 GMT+00:00 2006, Unc
28、ontrolled Copy, (c) BSI 3 4.2 Continuous-scanning method Based on the DSC principle (see ISO 11357-1) and the definition of specific heat capacity given in 3.2, the following relations can be obtained: spsp pspecimenrunblank run mcPP (3) calcal pcalibrationrunblank run mcPP (4) where P is the heat f
29、low rate (dQ/dt); superscripts sp and cal represent specimen and calibration material, respectively (see Figure 1). When specimenrun P, calibrationrun P and blank run P are measured, sp p c can be calculated using Equation (6), since the values of cal p c, sp m and cal m are known: spsp specimenrunb
30、lank runp calcal calibrationrunblank run p PPmc PP mc = (5) () () cal specimenrunblank run spcal pp sp calibrationrunblank run mPP cc mPP = (6) 4.3 Stepwise-scanning method In the stepwise-scanning method, the total temperature range to be scanned is divided into small intervals and a complete deter
31、mination consisting of the three runs mentioned in 4.1 is performed for each temperature interval. Upon integration of the heat flow rate curve, the total heat Q consumed in the interval can be obtained. Dividing Q by the temperature interval T and the mass of the specimen gives the specific heat se
32、e Equation (1): spblank spsp p pp QQ mc TT (7) calblank calcal p pp QQ mc TT (8) Keeping the temperature intervals T constant, combining Equations (7) and (8) results in: calspblank spcal pp spcalblank mQQ cc mQQ = (9) 5 Apparatus 5.1 DSC apparatus See ISO 11357-1:1997, Subclause 5.1. BS ISO 11357-4
33、:2005 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:16:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 4 5.2 Pans See ISO 11357-1:1997, Subclause 5.2. The pans for the test specimen and the reference specimen (calibration material) shall be of the same shape and material and their masses s
34、hall not differ by more than 0,1 mg. NOTE The same blank run and calibration run can be used for several measurements, if the instrument is sufficiently stable and the difference in mass between the calibration material pan and the empty pan is corrected for. An adequate correction can be obtained b
35、y adding the term cp,pan(T)m to the heat flow rate of the calibration run, where cp,pan(T) is the specific heat capacity of the calibration pan as a function of temperature, is the heating rate and m is the difference in mass between the calibration pan and the empty pan. The same procedure can also
36、 be used for correcting differences in mass between the specimen run and the blank run. 5.3 Analytical balance See ISO 11357-1:1997, Subclause 5.3. 6 Test specimen See ISO 11357-1:1997, Clause 6. 7 Test conditions and specimen conditioning See ISO 11357-1:1997, Clause 7. 8 Procedure 8.1 Selection of
37、 pans Prepare three pans and their lids and weigh the pans together with their lids. The total mass shall not differ by more than 0,1 mg (see 5.2). In other respects, such as material, size, pan type (open or sealed), the pans shall be identical. 8.2 Setting up the apparatus and adjustment of isothe
38、rmal baselines 8.2.1 Place a pair of empty pans with lids in the DSC sample and reference holders. 8.2.2 If using a continuous-scan programme: a) Set the start and end temperatures (Ts and Tf). The start temperature Ts should be at least 30 K lower than that at which data is first required. NOTE 1 W
39、hen more precise results are required over a wide temperature range, the overall range can be divided into two (or more) smaller ranges, each 50 K to 100 K wide. The start temperature Ts of the second range should be 30 K lower than the end temperature Tf of the first temperature range to ensure suf
40、ficient overlap. b) Set the scanning rate. c) Set the time interval between the isothermal stages I and II (see Figure 1) and allow the respective isothermal baselines to stabilize. This interval will usually be between 2 min and 10 min. NOTE 2 Some calorimeters, e.g. those of the Calvet type, may n
41、eed up to 30 min before the baseline stabilizes. BS ISO 11357-4:2005 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:16:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 5 8.2.3 If using a stepwise-scan programme: When the specific heat capacities of the samples do not significantly depend on
42、the temperature, the stepwise-scanning method can be used in which the integration of the heat flow over small temperature intervals gives a set of individual specific heat values for the temperature intervals considered. Attention shall be paid to the following points: a) The time interval between
43、the isothermal stages shall be sufficiently long to obtain a stable baseline. b) This method shall not be used over a temperature range in which first-order phase transitions occur. The stepwise scan is performed as follows: 1) Set the start and end temperatures (Ts and Tf). 2) Set the temperature i
44、ncrement preferably to 5 K to 10 K. 3) Set the temperature-scanning rate to 5 Kmin1 or 10 Kmin1. 4) Set the time interval between the isothermal stages, usually to between 2 min and 10 min. 8.2.4 Set the sensitivity of the heat flow rate in order to obtain an ordinate span of at least 80 % of full s
45、cale (see Figure 1). 8.2.5 Adjust the apparatus so that the isothermal baselines before and after the heating stage are at the same ordinate level. If microcomputer-based systems are used, the isothermal baselines can be adjusted to the same ordinate level after the data has been acquired. However,
46、it is strongly recommended that baseline adjustment is done before any measurements are made in order to improve the accuracy of the results. If a conventional pen recorder is used, proper apparatus adjustment is crucial to minimize differences in isothermal baseline level. Check that adjustment of
47、the baselines of the respective DSC curves results in the same ordinate level. If the baseline reproducibility is poor, readjust the apparatus and repeat the determination. NOTE Other reasons for poor baseline reproducibility can be contamination of the sample pan, the position of the lid, the stabi
48、lity of the purge gas flow rate, sample decomposition, sample evaporation, chemical reaction between pan and sample, etc. 8.2.6 Execute the temperature programme set as described in 8.2.2 or 8.2.3. Figure 2 shows a typical DSC curve obtained in the continuous-scanning mode whereas Figure 3 shows a D
49、SC curve obtained in the stepwise-scanning mode. 8.3 Measurement of specific heat capacity of calibration material Using an analytical balance, weigh a calibration material, such as -alumina (synthetic sapphire) of 99,9 % or higher purity, into one of the pans prepared in 8.1. Put the pan containing the calibration material, with the lid, in the sample